Removal of signal errors for differential satellite positioning systems
First Claim
1. A method for reducing the contributions of receiver noise signal error and multipath signal error from signals received in a Satellite Positioning System (SATPS) from one or more SATPS satellites, the method comprising the steps of:
- providing one or more SATPS satellites, numbered j=1, 2, . . . , each of which broadcasts SATPS signals including indicia that are specific to that satellite;
providing one or more SATPS stations, numbered i=1, 2, . . . , each SATPS station including an SATPS signal antenna and associated SATPS signal receiver/processor, whose location coordinates are accurately known, that receives from SATPS satellite number j and processes the SATPS signals as pseudorange signals PRi,j (t) and as carrier phase signals Φ
i,j (t) that vary with time t, for a sequence of selected signal sampling times {tn }n ;
for a selected time t0 and a subsequent sampling time tn, forming a difference signal DDi,j (tn ;
t0)=PRi,j (tn)-PRi,j (t0)-[Φ
i,j (tn)-Φ
i,j (t0)];
forming a difference signal DDi,j (tn ;
tn-1)=PRi,j (tn)-PRi,j (tn-1)-[Φ
i,j (tn)-Φ
i,j (tn-1)];
passing the signal DDi,j (tn ;
tn-1) through a first statistical processing filter having a first selected filter time constant τ
1 that lies in the range 50-500 sec, to produce a first output signal DD1i,j (tn ;
tn-1);
passing the signal DDi,j (tn ;
t0) through a second statistical processing filter having a second selected filter time constant τ
2 that lies in the range 5-20 sec, to produce a second output signal DD2i,j (tn ;
t0);
passing the signal DDi,j (tn ;
t0) through a third statistical processing filter having a third selected filter time constant τ
3 that lies in the range 50-500 sec to produce a third output signal DD3i,j (tn ;
t0);
forming a difference signal DD4i,j (tn ;
t0)=DD3i,j (tn ;
t0)-DD2i,j (tn ;
t0) as a fourth output signal;
forming a difference signal DD5i,j (tn ;
t0)=DDi,j (tn ;
t0)-DD4i,j (tn ;
t0) as a fifth output signal;
passing the fifth output signal DD5i,j (tn ;
t0) through a fourth statistical processing filter having a fourth selected filter time constant τ
4 that lies in the range 50-500 sec, to produce a sixth output signal DD6i,j (tn ;
t0);
identifying the output signal DD1i,j (tn ;
t0) with an SATPS signal with SATPS receiver noise error reduced or removed; and
identifying the output signal DD6i,j (tn ;
t0) with an SATPS signal with SATPS multipath signal error and receiver noise error reduced or removed.
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Accused Products
Abstract
Method and apparatus for reducing the contributions of receiver noise signal error and multipath signal error from signals received in a Satellite Positioning System (SATPS) from one or more SATPS satellites by formation and appropriate filtering of differences of signals DD that are differences of SATPS signals received by the SATPS receiver/processor. A difference signal DD of code-phase-derived delta range signals and carder-phase-derived delta range signals is formed, and this difference signal is passed through a first statistical processing filter with an associated time constant τ1 in the approximate range 50-500 sec, to produce smoothed or filtered signal with the estimated receiver noise error reduced or removed. The difference signal DD is passed through second and third statistical processing filters having associated time constants τ2=5-20 sec and τ3=50-500 sec, and the difference of the output signals of the second and third statistical processing filters is formed and subtracted from DD to form a new difference signal. This new difference signal is passed through a fourth statistical processing filter with an associated time constant τ4=50-500 sec, to produce a smoothed or filtered signal with the estimated multipath signal error and estimated receiver noise error reduced or removed.
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Citations
19 Claims
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1. A method for reducing the contributions of receiver noise signal error and multipath signal error from signals received in a Satellite Positioning System (SATPS) from one or more SATPS satellites, the method comprising the steps of:
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providing one or more SATPS satellites, numbered j=1, 2, . . . , each of which broadcasts SATPS signals including indicia that are specific to that satellite; providing one or more SATPS stations, numbered i=1, 2, . . . , each SATPS station including an SATPS signal antenna and associated SATPS signal receiver/processor, whose location coordinates are accurately known, that receives from SATPS satellite number j and processes the SATPS signals as pseudorange signals PRi,j (t) and as carrier phase signals Φ
i,j (t) that vary with time t, for a sequence of selected signal sampling times {tn }n ;for a selected time t0 and a subsequent sampling time tn, forming a difference signal DDi,j (tn ;
t0)=PRi,j (tn)-PRi,j (t0)-[Φ
i,j (tn)-Φ
i,j (t0)];forming a difference signal DDi,j (tn ;
tn-1)=PRi,j (tn)-PRi,j (tn-1)-[Φ
i,j (tn)-Φ
i,j (tn-1)];passing the signal DDi,j (tn ;
tn-1) through a first statistical processing filter having a first selected filter time constant τ
1 that lies in the range 50-500 sec, to produce a first output signal DD1i,j (tn ;
tn-1);passing the signal DDi,j (tn ;
t0) through a second statistical processing filter having a second selected filter time constant τ
2 that lies in the range 5-20 sec, to produce a second output signal DD2i,j (tn ;
t0);passing the signal DDi,j (tn ;
t0) through a third statistical processing filter having a third selected filter time constant τ
3 that lies in the range 50-500 sec to produce a third output signal DD3i,j (tn ;
t0);forming a difference signal DD4i,j (tn ;
t0)=DD3i,j (tn ;
t0)-DD2i,j (tn ;
t0) as a fourth output signal;forming a difference signal DD5i,j (tn ;
t0)=DDi,j (tn ;
t0)-DD4i,j (tn ;
t0) as a fifth output signal;passing the fifth output signal DD5i,j (tn ;
t0) through a fourth statistical processing filter having a fourth selected filter time constant τ
4 that lies in the range 50-500 sec, to produce a sixth output signal DD6i,j (tn ;
t0);identifying the output signal DD1i,j (tn ;
t0) with an SATPS signal with SATPS receiver noise error reduced or removed; andidentifying the output signal DD6i,j (tn ;
t0) with an SATPS signal with SATPS multipath signal error and receiver noise error reduced or removed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for reducing the contributions of receiver noise signal error and multipath signal error from signals received in a Satellite Positioning System (SATPS) from one or more SATPS satellites, the method comprising the steps of:
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providing one or more SATPS satellites, numbered j=1, 2, . . . , each of which broadcasts SATPS signals including indicia that are specific to that satellite; providing one or more SATPS stations, numbered i=1, 2, . . . , each SATPS station including an SATPS signal antenna and associated SATPS signal receiver/processor, whose location coordinates are accurately known, that receives from SATPS satellite number j and processes the SATPS signals as pseudorange signals PRi,j (t) and as carrier phase signals Φ
i,j (t) that vary with time t, for a sequence of selected signal sampling times {tn }n ;for a selected time t0 and a subsequent sampling time tn, forming a difference signal DDi,j (tn ;
t0)=PRi,j (tn)-PRi,j (t0)-[Φ
i,j (tn)-Φ
i,j (t0)];forming a difference signal DDi,j (tn ;
tn-1)=PRi,j (tn)-PRi,j (tn-1)-[Φ
i,j (tn)-Φ
i,j (tn-1)];passing the signal DDi,j (tn ;
tn-1) through a first statistical processing filter having a first selected filter time constant τ
1 that lies in the range 50-500 sec, to produce a first output signal DD1i,j (tn ;
tn-1);passing the signal DDi,j (tn ;
t0) through a second statistical processing filter having a second selected filter time constant τ
2 that lies in the range 5-20 sec, to produce a second output signal DD2i,j (tn ;
t0);forming a difference signal DD5i,j (tn ;
t0)=DDi,j (tn ;
t0)-DD2i,j (tn ;
t0) as a fifth output signal;passing the output signal DD5i,j (tn ;
t0) through a third statistical processing filter having a third selected filter time constant τ
4 that lies in the range 50-500 sec, to produce an output signal DD6i,j (tn ;
t0);identifying the output signal DD1i,j (tn ;
t0) with an SATPS signal with SATPS receiver noise error reduced or removed; andidentifying the output signal DD6i,j (tn ;
t0) with an SATPS signal with SATPS multipath signal error and receiver noise error reduced or removed.
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19. A method for reducing the contributions of receiver noise signal error and multipath signal error from signals received in a Satellite Positioning System (SATPS) from one or more SATPS satellites, the method comprising the steps of:
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providing one or more SATPS satellites, numbered j=1, 2, . . . , each of which broadcasts SATPS signals including indicia that are specific to that satellite; providing one or more SATPS stations, numbered i=1, 2, . . . , each SATPS station including an SATPS signal antenna and associated SATPS signal receiver/processor, whose location coordinates are accurately known, that receives from SATPS satellite number j and processes the SATPS signals as pseudorange signals PRi,j (t) and as carrier phase signals Φ
i,j (t) that vary with time t, for a sequence of selected signal sampling times {tn }n ;for a selected time t0 and a subsequent sampling time tn, forming a difference signal DDi,j (tn ;
t0)=PRi,j (tn)-PRi,j (t0)-[Φ
i,j (tn)-Φ
i,j (t0)];forming a difference signal DDi,j (tn ;
tn-1)=PRi,j (tn)-PRi,j (tn-1)-[Φ
i,j (tn)-Φ
i,j (tn-1)];passing the signal DDi,j (tn ;
tn-1) through a first statistical processing filter having a first selected filter time constant τ
1 that lies in the range 50-500 sec, to produce a first output signal DD1i,j (tn ;
tn-1);passing the signal DDi,j (tn ;
t0) through a notch filter having a selected filter time constant fC =1/τ
C that lies in the range 0.002-0.02 Hz to produce a third output signal DD3i,j (tn ;
t0);forming a difference signal DD5i,j (tn ;
t0)=DDi,j (tn ;
t0)-DD3i,j (tn ;
t0) as an output signal;passing the fifth output signal DD5i,j (tn ;
t0) through a fourth statistical processing filter having a fourth selected filter time constant τ
4 that lies in the range 50-500 sec, to produce an output signal DD6i,j (tn ;
t0);identifying the output signal DD1i,j (tn ;
t0) with an SATPS signal with SATPS receiver noise error reduced or removed; andidentifying the output signal DD6i,j (tn ;
t0) with an SATPS signal with SATPS multipath signal error and receiver noise error reduced or removed.
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Specification